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参数资料
| 型号： | LT1571 |
| 厂商： | Linear Technology Corporation |
| 英文描述： | Octal Bus Transceivers 20-SOIC 0 to 70 |
| 中文描述： | 恒流/恒压电池充电器预置电压和终止旗 |
| 文件页数： | 9/16页 |
| 文件大小： | 201K |
| 代理商： | LT1571 |
9
LT1571 Series
Lithium-Ion Charging
The circuit in Figure 4 uses the 28-pin LT1571-2 to charge
lithium-ion batteries at a constant 1A until the battery
voltage reaches 8.4V preset battery voltage. The charger
will then automatically go into a constant-voltage mode
with current decreasing to near zero over time as the
battery reaches full charge.
Lithium-Ion Charge Completion
Some battery manufacturers recommend termination of
constant-voltage float mode after charge current has
dropped below a specified level (typically around 10% to
20% of the full current) and a further time-out period of 30
minutes to 90 minutes has elapsed. Check with manufac-
turer for details. The LT1571 provides a signal at the FLAG
pin when the charger is in voltage mode and charge
current has reduced to approximately 20% of full current.
Note that full current is (2.465V
×
2000)/R
PROG
. Compara-
tor E6 in the Block Diagram compares the charge current
sample I
PROG
to the output current I
VA
voltage amplifier
VA. When the charge current drops to 20% of full current,
I
PROG
will be equal to 0.25 I
VA
and the open-collector
output V
FLAG
will go low. This signal can be used to start
an external timer or to terminate the charge. When this
feature is used, a capacitor of at least 0.1
μ
F is required at
CAP pin to filter out the switching noise and a pull-up
resistor is also needed at FLAG pin.
Charge Termination Flag Threshold Setting
The charge termination flag threshold can be reduced
from the default 20% level to as low as 7.5% of the
programmed full charge current. This is done by adding a
resistor R
CAP
from the CAP pin to ground (see Figure 5).
The formula for selecting the R
CAP
resistor is:
Threshold
R
R
or
R
R
Threshold
PROG
CAP
CAP
PROG
=
=
0 20
.
– (1 331
0 20
.
)
(1 331
)
–
R
PROG
is the charge current setting resistor.
Figure 5. Reducing Charge Termination Threshold
Figure 4. 200kHz Charging Lithium Batteries (Efficiency at 1A > 87%)
SW
V
CC
PROG
4.93k
100k
V
11V
TO 26V
+
1571 F04
C1
0.22
μ
F
C
IN
*
10
μ
F
L1**
33
μ
H
LT1571-2
D1
MBRM120T3
D3
MBRM120T3
D2
MMBD914L
SELECT
SENSE
GND
CAP
C
OUT
22
F
TANT
8.4V
0.3
μ
F
0.1
μ
F
1k
1
μ
F
NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED
*
COILTRONICS CTX33-2
BOOST
+
V
C
BAT
BAT2
FLAG
300
R
CAP
CAP
0.1
μ
F
LT1571
1571 F05
APPLICATIOU
W
U
U
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PDF描述 |
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| LT1573C | Low Dropout PNP Regulator Driver |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1571-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Constant-Current/ Constant-Voltage Battery Charger with Preset Voltage and Termination Flag |
| LT-1571-111-012 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1571-111-024 | 制造商:Carling Technologies 功能描述:SWITCH, TOGGLE, LTD, SP, 10A, ON-OFF-(ON) 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1571-111-125 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1571-112-125 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
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